I would not risk it. Check in at SGN is at least 3 hours unless you flying business or first. The domestic terminal is separate from the international terminal so you have to wait and pickup your baggage then walk to the international terminal, about 400 yards. The weather factor compounds the problem.
I would fly into SGN the night before and party until you drop. There are cheap hotel that you can rent by the hour, just check with the taxi driver. Be able to speak Vietnamese would be a plus in finding and negotiating for a hotel.